Human beings are the unequivocal world champions of niceness. We act kindly not only towards people who belong to our own social groups or can reciprocate our generosity, but also towards strangers thousands of miles away who will never know we helped them. All around the world, people sacrifice their resources, well being, and even their lives in the service of others.

For behavioral scientists, the great and terrible thing about altruism—behavior that helps others at a cost to the helper—is its inherent contradictions. Prosocial behaviors appear to contradict economic and evolutionary axioms about how humans should behave: selfishly, nasty and brutish, red in tooth and claw, or whichever catchphrase you prefer. After all, how could organisms that sacrifice for others survive, and why would nature endow us with such self-defeating tendencies?

In recent decades, researchers have largely solved this problem, offering reasons that perfectly self-oriented organisms might behave altruistically. Solving the "altruism paradox" becomes trivial when individuals help family members (thus advancing helpers' genes) or others who can reciprocate (increasing helpers' chances of future gains) or help others in public (enhancing helpers' reputation). We see these motives at work all around us, in parenting, favors for bosses, and opera patrons donating just enough to get their names on the "gold donor" plaques in theater lobbies.

More recently, my colleagues and I, as well as other neuroscientists, uncovered another "selfish"motive for altruism: helping others simply feels good. Giving to others engages brain structures associated with reward and motivation, similar to those that come online when people see beautiful faces, win money, or eat chocolate. Further, "reward-related" brain activity associated with helping track people's willingness to act generously. This doesn't mean that altruism is the psychological equivalent of Ben and Jerry's, but it does provide converging evidence for James Andreoni's idea that generosity produces a hedonic "warm glow."

One common response I receive when presenting this work has grown increasingly bothersome. Often, an audience member will claim that if people experience helping as rewarding, then their actions are not "really" altruistic at all. The claim as I understand it traces back to the Kantian notion—embedded in the "cost to the helper" section of altruism's definition—that virtuous action is motivated by principle alone, and that cashing in on that action, whether through material gain or psychological pleasure, disqualifies it as being virtuous. Oftentimes, this contention devolves into long, animated, and (to my mind) useless attempts to find space for true altruism amid an avalanche of ulterior motives.

This altruism hierarchy, with a near-mystic "true" altruism residing somewhere in the distance and our sullied attempts at it crowding real life, is widespread. It also plays out directly in people’s judgment. For instance, a study published yesterday by George Newman and Daylain Cain demonstrated that people judge people as less moral when they act altruistically and gain in the process, than when they gain from clearly non-altruistic behavior. In essence, people view "tainted altruism" as worse than no altruism at all.

I think the altruism hierarchy should be retired. I do believe that people often help others absent the goal of any personal gain. Dan Batson, Philip Kitcher, and others have done the philosophical and empirical work of distinguishing other-oriented and self-oriented motives for prosociality. But I also believe that the reservation of terms such as "pure"or "real" for actions bereft of any personal gain is less than useful.

This is for two reasons, which both connect with the broader idea of self-negation. First, the altruism hierarchy is logically self-negating. Attempts to identify true altruism often boil down to redacting motivation from behavior altogether. The story goes that in order to be pure, helping others must dissociate from personal desire (to kiss up, look good, feel rewarded, and so forth). But it is logically fallacious to think of any human behavior as amotivated. De facto, when people engage in actions, it is because they want to. This could represent an overt desire to gain personally, but could also stem from previous learning (for instance, that helping others in the past has felt good or provided personal gain) that translates into an intuitive prosocial preference. Disqualifying self-motivated behavior from being altruistic obscures the universality of motivation in producing all behavior, generous or not.

Second, the altruism hierarchy is morally self-negating. It often appears to me that critics of "impure" altruism chide helpers for acting in human ways, for instance by doing things that feel good. The ideal, then, seems to entail acting altruistically while not enjoying those actions one bit. To me, this is no ideal at all. I think it's profound and downright beautiful to think that our core emotional makeup can be tuned towards others, causing us to feel good when we do. Color me selfish, but I'd take that impure altruism over a de-enervated, floating ideal any day.